Department of Molecular Biology and Biochemistry, Simon Fraser University , Burnaby, British Columbia, Canada V5A 1S6.
Biochemistry. 2014 Jan 28;53(3):450-61. doi: 10.1021/bi401457r. Epub 2014 Jan 15.
Membrane-induced amphipathic helices (m-AH) can act as membrane curvature sensors by binding preferentially to hydrophobic lipid packing defects enriched in curved surfaces. Reliance on hydrophobicity and membrane curvature for binding is enhanced when electrostatic interactions are weak. We probed the role of modifying membrane and protein charge on the curvature sensing of two m-AH-containing proteins, CTP:phosphocholine cytidylyltransferase (CCT) and α-synuclein (α-syn). The m-AH domains in both proteins are flanked by disordered tails with multiple phosphoserines (CCT) or acidic residues (α-syn), which we mutated to glutamate or serine to modify protein charge. Analysis of binding to vesicles of varying curvature showed that increasing the negative charge of the tail region decreased the binding strength and augmented the curvature dependence, especially for CCT. We attribute this to charge repulsion. Conversely, increasing the membrane negative charge dampened the curvature dependence. Our data suggest that discrimination of curved versus flat membranes with high negative charge could be modulated by phosphorylation.
膜诱导的两亲性螺旋（m-AH）可以通过优先结合富含在弯曲表面的疏水性脂质堆积缺陷来充当膜曲率传感器。当静电相互作用较弱时，结合对疏水性和膜曲率的依赖性增强。我们研究了修饰膜和蛋白质电荷对两种含 m-AH 的蛋白质（CTP：磷酸胆碱胞苷转移酶（CCT）和α-突触核蛋白（α-syn））曲率传感的作用。这两种蛋白质的 m-AH 结构域都被无序的尾巴包围，尾巴上有多个磷酸丝氨酸（CCT）或酸性残基（α-syn），我们将其突变为谷氨酸或丝氨酸以修饰蛋白质电荷。分析与不同曲率的囊泡的结合表明，增加尾部区域的负电荷会降低结合强度并增加曲率依赖性，尤其是对于 CCT。我们将其归因于电荷排斥。相反，增加膜的负电荷会减弱曲率依赖性。我们的数据表明，通过磷酸化可以调节带有高负电荷的弯曲与平面膜之间的区分。
